The present invention relates to new formulations which can be used to purify fresh water and sea water from pollutions of petroleum origin.
This type of pollution, which is caused by crude petroleum and its refinery fractions, and more generally by hydrocarbons, can be fought by using physico-mechanical techniques adapted to collect the pollutants, although in many cases these techniques cannot be used; it is then necessary to leave in place the major part of the pollutants in the least detrimental form possible, for a sufficient time to allow microorganisms affect a purifying degradation, these microorganisms being naturally present or added to the medium, for example as lyophilisates, the metabolism of which must be ensured.
It is also well known that the microflora found in the ground, in sediments, in fresh water or in sea water comprises several microbial species able to convert and assimilate most of the hydrocarbons and oil products, but the rate of the biochemical reactions and the intensity of the conversion are limited by several physico-chemical factors, particularly an insufficient concentration of the compounds supplying assimilable phosphorus and nitrogen to the microflora; another limitation results from the contact surface between oil and water whose interfacial surface, a privileged place for the degradation reactions, must be colonized by the purifying microflora.
It has long been known that the biodegradation of petroleum materials can be accelerated by adding fertilizers such as ammonium salts, nitrates and phosphates; however, in open medium, it is uneconomical to merely add these salts to water or to the polluted ground, since they have a too high solubility in water.
To obviate this disadvantage, several authors have proposed the use of oil-soluble compounds comprising nitrogen and phosphorus. The use of lecithin is thus proposed in the French Pat. No. 2 392 941, and the use of ureidic derivatives of organic aldehydes comprising at least 4 carbon atoms is disclosed in the French Pat. No. 2 346 292. The latter compounds have however the disadvantage of being expensive.
New inexpensive biodegradable formulations have now been discovered, which are both oil-dispersant and nutritive for microorganisms.